Electrophotographic image-forming machines are used to transfer images onto paper or other medium in both printing and copier systems. Generally, a photoconductor is selectively charged and optically exposed to form an electrostatic latent image on the photoconductor surface. Toner is deposited onto the charged photoconductor surface. The toner has a charge; thus, it will adhere to the photoconductor surface in areas corresponding to the electrostatic latent image. The toner image is transferred to the paper or other medium. The toned paper is heated by any of several methods including a fuser roller system and the toner in image-wise configuration is fused to the paper. The photoconductor is then refreshed—cleaned to remove any residual toner and charge—to make it ready for another image. The imaged paper is then passed to a document output collection area or tray where the user collects the finished, permanently imaged paper or documents.
The fuser roll used in the fuser roller system eventually becomes contaminated with a film or debris containing toner or by-products of toner and paper. This contamination usually takes the form of a film which eventually builds up and adversely affects the performance and life of the fuser roll.
This fuser roll contamination can generally occur in any fuser system of an electrophotographic printer or copier, and it causes marks on copy (MOC) in addition to marks caused by prior image history. Generally, the fuser roll becomes contaminated, as earlier noted, with toner and by-products of fuser chemical reactions which eventually can cause early failure of the entire fusing system.
Problems with toner debris on the fuser roller can eventually affect the pressure roll and also the quality and clarity of the imaged paper in contact with the fuser roller. As noted above, the life of the fuser roll can be substantially shortened if this contamination problem is not properly addressed. This results in increasing customer operating costs.
It is desired in the fusing process that minimal or no offset of the toner particles from the support to the fuser member takes place during normal operations. Toner particles offset onto the fuser member can subsequently transfer to other parts of the machine or onto the support in subsequent copying cycles, thereby increasing the image background, causing inadequate copy quality, causing inferior marks on the copy, or otherwise interfering with the material being copied there as well as causing toner contamination of other parts of the machine. The defect referred to “hot offset” occurs when the temperature of the toner is increased to a point where the toner particles liquefy and a splitting of the molten toner takes place during the fusing operation with a portion remaining on the fuser member. The hot offset temperature or degradation of the hot offset temperature is a measure of the release properties of the fuser member, and accordingly it is desirable to provide a fusing surface having a low surface energy to provide the necessary release.
The use of polymeric release agents having functional groups which interact with a fuser member to form a thermally stable, renewable self-cleaning layer having good release properties for electroscopic thermoplastic resin toners, is described in, for example, U.S. Pat. Nos. 4,029,827, 4,101,686, and 4,185,140, the disclosures of each of which are totally incorporated herein by reference.
In color or monochrome xerographic marking fusing systems and subsystems, silicone fluids are presently predominantly used as release agents. There are many associated defects and failure modes associated with the use of these fluids, especially when they are employed in machines printing full colors and requiring longer service life. Silicone is by nature chemically and physically susceptible to reaction with many other species in the environment, such as toner and toner additives, ink components, paper debris, etc. Side reactions with these species can lead to premature gelation, toner offset, slime, image defects, which ultimately lead to shortened component and subsystem operation life. This life shortfall directly impacts operation costs incurred by both manufacturers and customers. End use applications in particular, are negatively impacted by the use of amine-functional silicone fluids, as the amine functionality interacts with the surface of both coated and un-coated paper stocks. This leaves a persistent film on the surface that inhibits adhesives, UV overcoats write-ability, post-it notes use, book binding, and other end use elements from properly functioning.